Reverse transcription was performed using 100ng of each sample with M-MMLV Reverse Transcriptase from Promega.

Briefly, 100ng of DNased RNA was combined with oligo dT primers and brought up to a final volume of 15uL. Tubes were incubated for 5mins at 70oC in a PTC-200 thermal cycler (MJ Research), using a heated lid. Samples were immediately placed on ice.

A master mix of buffer, dNTPs, water, and M-MMLV reverse transcriptase was made, 10uL of the master mix was added to each sample, and mixed via finger flicking. Samples were incubated for 1hr at 42oC in a PTC-200 thermal cycler (MJ Research), using a heated lid, followed by a 5min incubation at 65oC.

Currently don’t have sufficient reagents to perform reverse transcription on the entire set of DNased RNA (control and 1hr.heat-shockedO.lurida ctenidia samples). To enable Jake to start testing out some of his primers while we wait for reagents to come in, Steven suggested I generate some cDNA for him to use.

Excluding the no template controls (NTC), all samples produced amplification. Will require DNasing before making cDNA.

Related to the qPCR I ran earlier today with these same primers, the efficiencies of the reactions on this plate are significantly better (i.e. normal; >80% efficiencies) than the earlier qPCR. The improved efficiency would also explain why the positive control comes up two cycles earlier on this run.

In the amplification plots below, the positive control reps are the two lines coming up at cycle ~20.

The following sample tubes (heat-shocked oyster ctenidia) were removed from -80C and thawed at RT:

42215 HC 1

42215 HC 2

42215 HC 3

42215 HC 4

42215 HC 5

42215 HC 6

42215 HC 7

42215 HC 8

42215 NC 1

42215 NC 2

42215 NC 3

42215 NC 4

42215 NC 5

42215 NC 6

42215 NC 7

42215 NC 8

42215 SC 1

42215 SC 2

42215 SC 3

42215 SC 4

42215 SC 5

42215 SC 6

42215 SC 7

42215 SC 8

NOTE: 0.1% DEPC-H2O used throughout this procedure was prepared on 7/15/2010 by me.

According to Jake’s notebook entry, the samples should have been previously homogenized in RNAzol RT (Molecular Research Center; MRC). However, none of the samples showed evidence of being homogenized:

Procedure:

Samples were homogenized with disposable pestle in their respective tubes and vortexed.

Added 400μL of 0.1% DEPC-H2O to each sample and vortexed 15s.

Incubated samples 15mins at RT.

Centrifuged tubes 15mins at RT @ 16,000g.

750μL of the supe was transferred to a clean tube, added equal volume of isopropanol (750μL), mixed by inversion (20 times), and incubated at RT for 15mins.

Centrifuged 12,000g for 10mins.

Discarded supe.

Washed pellets with 500μL of 75% EtOH (made with 0.1% DEPC-H2O) and centrifuged 4,000g for 3mins at RT. Repeated one time.

Removed EtOH and resuspended in 100μL of 0.1% DEPC-H2O. Most samples required vortexing to dissolve pellet.

Sample tubes were transferred to ice, quantified on the Roberts Lab NanoDrop1000, and stored @ -80C in their original box, pictured:

Excellent yields and pretty solid 260/280 ratios (>1.85). Interestingly, the 260/230 ratios aren’t so great (compared to yesterday’s isolations). I suspect that the reason for this is that there appeared to be more starting tissue in these samples than yesterday’s. The greater quantity of tissue explains the higher yields and could be tied to the decrease in the 260/230 ratios…

Anyway, things look good. Next step will be to check for gDNA carryover in these samples and yesterday’s samples.

Overall, the samples have excellent yields. The exceptions being the two samples that had less than 1mL of RNAzol RT in them to start (their yields are actually fine, but relative to all the other samples, they aren’t great). Should I have left them that way instead of adding additional RNAzol RT? Was there something wrong with these samples in the first place and that’s why they didn’t have a full 1mL of RNAzol RT in the tube already?

The 260/280 ratios are pretty good for most of the samples (>1.8), however I’d prefer to see RNA with 260/280 ratios >1.9.

The 260/230 ratios are amazing! The best I’ve seen coming straight out of an RNA isolation in a long time.

Eventually (once I’ve isolated RNA from the control set that corresponds to these heat shock samples), I’ll check for gDNA carryover and then, probably, DNase the RNA.

Samples were quantified using the Quant-It DNA BR Kit (Life Technologies/Invitrogen) according the manufacturer’s protocol. Standards were run in triplicate. Due to low sample volumes, only 1μL of each sample was used and was not replicated.

Plate was read on a Perkin Elmer plate reader using the Wallac software. The plate was measured three times, with each well measured for a one second duration on each read.

Not entirely surprising, but the fluorescence method is clearly the most conservative measurement of the three methods. However, I do find the difference between the Bioanalyzer and fluorescence measurements very surprising. I suspected the Bioanalyzer would underestimate the concentrations because I actively selected which peak regions to measure, possibly leaving out some aspect of the sample.

Regardless, will use the most conservative measurements (fluorescence) for decision making.

With our yields, we have insufficient DNA to conduct MeDIP and then subsequent bisulfite conversion and library prep on our own. The recovery from the MeDIP will result in too little input DNA for bisulfite conversion and, in turn, library prep.

However, we do have sufficient quantities of starting DNA (>200ng) for Epigentek’s MeDIP Methyl-seq. I have contacted Epigentek to see if their procedure includes bisulfite conversion after MeDIP (which the website workflow suggests that it does not).

I previously checked Claire’s sheared DNA on the Bioanalyzer to verify the fragment size and to quantify the samples. Looking at her notebook, her numbers differ greatly from the Bioanalyzer, possibly due to the fact that the DNA1000 assay chip used only measures DNA fragments up to 1000bp in size. If her shearing was incomplete, then there would be DNA fragments larger than 1000bp that wouldn’t have been measured by the Bioanalyzer. So, I decided to quantify the samples on the NanoDrop1000 (ThermoFisher) again.

The NanoDrop is known to overestimate sample quantities due to the indiscriminate nature of UV spectrophotometry and that could be the reason for the large discrepancy between the two measurements (i.e. RNA carryover may lead to overestimation). As such, I’ll quantify the samples using a fluorescence-based assay for double stranded DNA tomorrow in hopes of getting the most accurate measurement.

To complement MBD ChiP-seq data and RNA-seq data that we have from this experiment, we want to generate, at a minimum, some BS-seq data from the same C.gigas individuals used for the other aspects of this experiment. Claire had previously isolated DNA and sheared the DNA on 20140108. If possible, we’d like to perform MBD enrichment, but the current quantities of DNA may prevent us from this.

To quantify the DNA and evaluate the shearing profile, I ran 1μL of each of the following mantle pre-/post-heat shock samples on a DNA 1000 chip (Agilent) on the Agilent 2100 Bioanalyzer. in the Seeb Lab:

Claire’s notebook entry doesn’t ever specify what her target shear size was, but the Bioanalyzer analysis suggests an average size of ~500bp.

Also interesting to note is that Claire’s sample concentrations (as measured on the NanoDrop1000) are significantly greater than what is calculated by the Bioanalyzer. Since the Bioanalyzer chip used (DNA1000) only goes to 1000bp, is it possible the differences in concentrations is due to incomplete shearing of the samples (e.g. a significant portion of the DNA is >1000bp in size and thus not factored in to the Bioanlyzer concentrations calculations)?

Will check sample volumes and determine total amount of remaining DNA for each sample and then assess how to proceed next (i.e. MBD or just BS-seq).

UPDATE 20150226:

Sample volumes were measured and total quantity (ng) of DNA in each sample were added to the spreadsheet above.

Based on the quantities of DNA we have for each sample, will discuss sequencing options (e.g. MBD or not, self-prepare libraries or not, etc) with Steven.